1. Field of the Invention
The present invention relates to an intersomatic fusion and setting system for vertebrae. The system includes at least one open internal cage receiving spongy bone and designed to be interposed between two vertebrae during diskectomy and the system is capable of installing a bone graft or material encouraging intersomatic fusion, thereby encouraging fusion between the two vertebrae concerned.
2. Description of Related Art
Similar cages are known, for example, from the following patent applications: FR 2 703 580; EP 493 698; EP 599 419; FR 2 124 815; EP 307 241; EP 615 428.
These cages are generally ovoid or parallelepipedal in shape. They are rigid, made of metal or of a biocompatible material, and designed to receive spongy bone via open top and bottom faces.
Although cages of the above type generally give good results, it is nevertheless true that in some cases it is necessary to position the cage and to ensure that it cannot move so as to be sure of avoiding any possible migration or risk of secondary displacement of the cage.
A prosthesis is also known from document EP 0 179 695 comprising an implant forming an open internal cage designed to receive spongy bone or bone substitute. The cage is fitted with a plate extending in a plane substantially perpendicular to the insertion plane of the cage, having two holes on either side thereof for passing respective screws for anchoring in each of the two adjacent vertebrae that are to be secured together. The implant which is in the form of a length of a cylinder is designed to be inserted between two adjacent vertebrae from which portions of the vertebral bodies have been removed. Such a prosthesis has a drawback concerning the anchor screws which are subjected to large forces that can cause the screws to become at least partially disconnected from the vertebrae, and thus allowing the cage to be relatively mobile.